private static void AddSingleLiteral(uint pixel, bool useColorCache, ColorCache colorCache, Vp8LBackwardRefs refs)
{
PixOrCopy v;
if (useColorCache)
{
int key = colorCache.GetIndex(pixel);
if (colorCache.Lookup(key) == pixel)
{
v = PixOrCopy.CreateCacheIdx(key);
}
else
{
v = PixOrCopy.CreateLiteral(pixel);
colorCache.Set((uint)key, pixel);
}
}
else
{
v = PixOrCopy.CreateLiteral(pixel);
}
refs.Add(v);
}
public void DecodeImageData(Vp8LDecoder decoder, Span <uint> pixelData)
{
int lastPixel = 0;
int width = decoder.Width;
int height = decoder.Height;
int row = lastPixel / width;
int col = lastPixel % width;
const int lenCodeLimit = WebpConstants.NumLiteralCodes + WebpConstants.NumLengthCodes;
int colorCacheSize = decoder.Metadata.ColorCacheSize;
ColorCache colorCache = decoder.Metadata.ColorCache;
int colorCacheLimit = lenCodeLimit + colorCacheSize;
int mask = decoder.Metadata.HuffmanMask;
Span <HTreeGroup> hTreeGroup = GetHTreeGroupForPos(decoder.Metadata, col, row);
int totalPixels = width * height;
int decodedPixels = 0;
int lastCached = decodedPixels;
while (decodedPixels < totalPixels)
{
int code;
if ((col & mask) == 0)
{
hTreeGroup = GetHTreeGroupForPos(decoder.Metadata, col, row);
}
if (hTreeGroup[0].IsTrivialCode)
{
pixelData[decodedPixels] = hTreeGroup[0].LiteralArb;
this.AdvanceByOne(ref col, ref row, width, colorCache, ref decodedPixels, pixelData, ref lastCached);
continue;
}
this.bitReader.FillBitWindow();
if (hTreeGroup[0].UsePackedTable)
{
code = (int)this.ReadPackedSymbols(hTreeGroup, pixelData, decodedPixels);
if (this.bitReader.IsEndOfStream())
{
break;
}
if (code == PackedNonLiteralCode)
{
this.AdvanceByOne(ref col, ref row, width, colorCache, ref decodedPixels, pixelData, ref lastCached);
continue;
}
}
else
{
code = (int)this.ReadSymbol(hTreeGroup[0].HTrees[HuffIndex.Green]);
}
if (this.bitReader.IsEndOfStream())
{
break;
}
// Literal
if (code < WebpConstants.NumLiteralCodes)
{
if (hTreeGroup[0].IsTrivialLiteral)
{
pixelData[decodedPixels] = hTreeGroup[0].LiteralArb | ((uint)code << 8);
}
else
{
uint red = this.ReadSymbol(hTreeGroup[0].HTrees[HuffIndex.Red]);
this.bitReader.FillBitWindow();
uint blue = this.ReadSymbol(hTreeGroup[0].HTrees[HuffIndex.Blue]);
uint alpha = this.ReadSymbol(hTreeGroup[0].HTrees[HuffIndex.Alpha]);
if (this.bitReader.IsEndOfStream())
{
break;
}
pixelData[decodedPixels] = (uint)(((byte)alpha << 24) | ((byte)red << 16) | ((byte)code << 8) | (byte)blue);
}
this.AdvanceByOne(ref col, ref row, width, colorCache, ref decodedPixels, pixelData, ref lastCached);
}
else if (code < lenCodeLimit)
{
// Backward reference is used.
int lengthSym = code - WebpConstants.NumLiteralCodes;
int length = this.GetCopyLength(lengthSym);
uint distSymbol = this.ReadSymbol(hTreeGroup[0].HTrees[HuffIndex.Dist]);
this.bitReader.FillBitWindow();
int distCode = this.GetCopyDistance((int)distSymbol);
int dist = PlaneCodeToDistance(width, distCode);
if (this.bitReader.IsEndOfStream())
{
break;
}
CopyBlock(pixelData, decodedPixels, dist, length);
decodedPixels += length;
col += length;
while (col >= width)
{
col -= width;
row++;
}
if ((col & mask) != 0)
{
hTreeGroup = GetHTreeGroupForPos(decoder.Metadata, col, row);
}
if (colorCache != null)
{
while (lastCached < decodedPixels)
{
colorCache.Insert(pixelData[lastCached]);
lastCached++;
}
}
}
else if (code < colorCacheLimit)
{
// Color cache should be used.
int key = code - lenCodeLimit;
while (lastCached < decodedPixels)
{
colorCache.Insert(pixelData[lastCached]);
lastCached++;
}
pixelData[decodedPixels] = colorCache.Lookup(key);
this.AdvanceByOne(ref col, ref row, width, colorCache, ref decodedPixels, pixelData, ref lastCached);
}
else
{
WebpThrowHelper.ThrowImageFormatException("Webp parsing error");
}
}
}
